1. Field of the Invention
This invention relates to spinning finishes for synthetic filament fibers containing as lubricant polyesters having hydrophilic and hydrophobic components in the molecule. The polyesters are block copolymers of hydrophilic polyethylene glycols and hydrophobic diols selected from the group consisting of polypropylene glycols, polytetrahydrofurans, polycaprolactone diols, hydrogenation products of ricinoleic acid esters, dimeric diols, 1,2-alkanediols and .alpha.,.omega.-alkanediols and polybasic carboxylic acids and/or derivatives thereof linking the polyethylene glycols and hydrophobic diols.
All synthetic manmade fibers are provided immediately after the filament-forming process with finishes which are essential for the subsequent processing of the fibers. These finishes, which are generally known in German as "Spinnpraparationen (spinning finishes)" (cf. Ullmann Encyclopadie der technischen Chemie", Vol. 23, pages 7-9 Verlag Chemie, Weinheim 1983), provide the filaments wit the necessary surface slip between one another and between the filaments and the guide elements of the spinning machines. In addition to smoothness and filament compactness, fiber manufacturers generally expect spinning finishes to satisfy the following requirements: antistatic effect, good wetting of the filament, temperature stability, no metal corrosion, no deposits on stretching a texturing units, ready removability from the fibers a physiological harmlessness. Since the lubricants enter t wastewater during removal from the fibers, for example before dyeing, biodegradable lubricants are desirable.
2. Discussion of Related Art
The lubricants in spinning finishes are intended above all to provide the filaments with the necessary surface slip. At the same time, however, the lubricants must be temperature-stable, non-corrosive, readily removable from the fibers and physiologically harmless so that the requirements which the spinning finishes are required to meet can be satisfied. Typical lubricants for spinning finishes are vegetable, animal and mineral oils or even synthetic esters, silicones, polyethers, ethoxylated fatty acids and the like (cf. Ullmanns Encyclopadie der technischen Chemie, Vol. 23, pages 7-9, Verlag Chemie, Weinheim 1983).
In addition, spinning finishes for synthetic filament fibers should be capable of withstanding high temperatures such as occur in the texturing of polyester and polyamide fibers. Accordingly, so-called ester oils, i.e. esters of relatively high fatty acids with long-chain fatty alcohols, are often used as lubricants in such spinning finishes. According to Japanese patent publication JP-A-02/068367 (cf. Chemical Abstracts, Vol. 113:25510f), polyethylene oxide/polypropylene oxide block copolymers, so-called Pluronics.RTM., may be used instead of the temperature-stable ester oils. Pluronics are capable of depolymerizing completely at relatively high temperatures. This is a particular advantage in texturing because deposits on filaments and texturing elements are avoided. However, fragments of the Pluronics, such as aldehydes, escape into the atmosphere during texturing, which can be harmful to human beings and the environment. In addition, Pluronics have the serious disadvantage that they are virtually non-biodegradable.
Spinning finishes for polyester fibers based or polyesters prepared from dicarboxylic acids, monocarboxylic acids and tetrahydrofuran/alkylene oxide random copolymer. are known from Japanese patent publication JP-A-63/23557 (cf. Chemical Abstracts, Vol. 110:156049y). However, these spinning finishes are also poorly biodegradable. According to Japanese patent publication JP-A-62/006982 (cf. Chemical Abstracts, Vol. 107:79426c), applied polyesters of terephthalic acid, ethylene oxide, propylene oxide and/or butylene oxide and, optionally, monocarboxylic acids or monohydric alcohols provide synthetic fibers with improved bindability and weavability. There is no reference to the significance of hydrophobic and hydrophilic components in the polyester molecule. In addition, the polyesters in question are exclusively polyesters based on aromatic terephthalic acid which is poorly biodegradable.
Polyesters containing hydrophilic and hydrophobic components in the molecule, which have been prepared from monoalcohols, dicarboxylic acids, secondary alcohols, polyethylene oxide and, optionally, polypropylene oxide, are known as emulsifiers in sizes containing epoxy resins for carbon fibers and glass fibers (cf. European patent application EP-A-03 93 665). According to the teaching of this patent application, it is crucial to the invention that the polyesters contain the polyethylene oxide units at the end of the polymer because it is only terminal polyethylene oxide units which are hydrophilic in character. In addition, these sizes of an epoxy resin and the polyesters are totally unsuitable as spinning finishes for synthetic fibers because the tacky epoxy resins would cause the synthetic filaments to adhere excessively to one another, resulting in filament breaks.
The problem addressed by the present invention was to provide spinning finishes for synthetic filament fibers which would contain lubricants having improved biodegradability. In addition, the lubricants would show good surface-slip properties by virtue of a hydrophobic component of the molecule and would readily be incorporable in water by virtue of a hydrophilic component of the molecule The lubricants would also be readily removable from the fibers and would show high temperature stability.